I've never been a big fan of Cameron, but there is something in Avatar which flirts with brilliance: the way he managed to include many of the current pop affairs disguised as metaphors in the movie storyline.
It's a lot easier now to explain to my folks (Dad is 77 now) how the internet works, and mostly, what collective intelligence is. I'll have surely to skip the part where he should hang a USB plug from the few silver hair remaining on his head, but apart from that, the big network Pandora is built upon is a beautiful analogy to the networked society we live in now a days.
On top of that, ecology is big on the flick, and Pandorians are truly tree huggers, bringing to the audience a not so subtle message of hey-we-should-stop-what-we-are-doing-and-save-the-world-now.
Cameron never hid the fact he is for the masses, and being so, the way the content is translated to the target is magnificent.
Make it beautiful and not so obvious. Pulverise a pop message with a little poetry. Your Gramma will eventually get it.